The growth of optical networks for voice and data communication has created a demand for high data-rate information-transfer capabilities. To enable such transfer capabilities, dense wavelength division multiplexing (DWDM) technology has been developed which allows transfer of multiple wavelength light beams over a single optical fiber enabling data transfer rates up to 40–100 Gb/s. High speed switching and routing devices comprise the core elements of the optical networks and allow dynamic control of the data traveling over the optical network. High data transmission rates impose significant demands on the functionality of the switching devices.
Many types of switches have been proposed, including electrical switches that convert the optical signal to an electrical signal and convert the switched electrical signal back to an optical signal, and optical switches that switch by deflecting light using mirrors. Electrical switches involve conversion steps that make these switches expensive and slow. Prior optical switches include switches having many small, movable mirrors that are controlled to direct optical signals through the switch. These switches have additional problems that limit their use in high speed systems. First, there are reliability problems due to the large number of small movable mirrors. Second, the switching times are limited by the physical movement of mirrors, and are not capable of the high-speed switching required for further optical communications systems.
Optical switches have also been proposed that route light between a plurality of inputs and outputs across a common waveguide. See, for example, commonly assigned U.S. Pat. No. 6,504,966 by Kato et al., incorporated herein by reference. These switches include an input side, the common waveguide, and an output side. Switching is accomplished by the routing any one of the input light beams through the common waveguide to a desired output, and is controlled by coordinated deflections of the light beam at the input and output sides. The input and output sides include a waveguide having an electro-optical material and specially shaped electrodes on opposite sides of the waveguide. The application of voltage differences across the electrodes modifies the refractive index, according to the voltages, within prism-shaped volumes of the electro-optical material. In particular, the electrodes are arranged to form multiple prism pairs. The shape of the prism pairs and the value of the modified refractive index within the prism pairs deflect an appropriately aligned incident beam within an angular deflection range.
Such switches have several limitations that result in a switch that is large or that is complicated to fabricate. For example, the use of only a few prism pairs to deflect light results in an angular deflection range that is small, and thus a long common waveguide is required to switch between one of a number of outputs. Alternatively, the number of prism pairs can be increased to provide a greater angular deflection range. The large number of prism pairs requires a complicated fabrication process and a large optical path for deflecting light.
Therefore, it would be desirable to have a switch for an optical communication system that overcomes the problems with prior optical switches and is faster, more reliable and less expensive to construct than current optical switches. It is also desirable for a switch to be rugged and compact.